Destacker



Feb. 15, 1955 Filed Aug. 26, 1949 w. L. VAN DoREN DESTACKER 5 Sheets-Sheet v3S nventor Mmmm L. #fm/,Doen

Gttomeg Feb. 1 5'. 1955 w. L.. VAN DOREN DEsTAcKER 5 Sheets-Sheet 4 Fled Aug. 26, 1949 Gtomeg Feb. 15, 1955 w. L.. VAN DoRl-:N

DEST ACKER 5 Sheef.s sheet 5 Filed Aug. 2e l 1949 Shoentor QUEEN m L W L M Gttorneg nasrxcm William Louis Van Deren, Wenatchee, Wash. Applicatie Ama 26, 1949, saisi No. 112,445 1o cmu. (ci. '2u-asiv l` do with a de-stacker whereby stacked boxes of apples or the like may be removed one at a time from the lower end of a stack for their advancement in succession on a oor level conveyor to a box dumping machine; it being the principal object of this'invention to provide a destacker that is eflicient and satisfactory in its operations that is relatively simple in its construction and mode or operation; that performs the work of receiving a stack of boxes therein and the successive removal of the stacked boxes one at a time from the lower end of the stack, and their advancement from the machine without any jar or jolt on the boxes that would be detrimental to their contents.

It is also an object of the present invention to provide a mechanism that departs in its mode of operation from the procedure of machines now generally in use in that the boxes are removed one at a time from the lower c nd of a stack instead of from the .upper end; this being accomplished by a lifting mechanism that operates intermittently to slightly lift that portion of a stack that is above the lowermost box, thus allowing a conveyor mechanism to advance the said lowermost box from the stack and from the machine; the lifted portion of the stack then being lowered onto a support and the operation by the lifting mechanism repeated, but each time lifting only that portion of the stack that is above the lowermost box.

Other objects of the invention reside in the details of construction and combination of parts, and in the mode of operation and control of the machine, as will hereinafter be fully described.

In accomplishing these and other objects of the mvention, I haveprovided the improved details of construction, the preferred forms of which are illustrated in the accompanying drawings, whereint Fig. 1 is a side view of a de-stacker embodying the improvements of the present invention therem, show ing a stack of boxes ready for advancement n ito the machine, and indicating in dotted lines, the position of the stack in the machine.

Fig. 2 is a detail of a part of the stack conveyor driving means.

Fig. 3 is a vertical, cross-section taken on the line 3-3 y in Fig. 1.

. Fig. 4 is a top view of the machine, asseen in Fig. 3. Fig. 5 is a side elevation showing the stack lifting cross head and its actuating means at one side of the machine. Fig. 6 is an enlarged, cross-sectional detail taken on the line 6`6' in Fig. 5, showing the relationship of the United States Patent O ice Patented Feb. 15, 1955 Fig. 13 is a perspective view of the end portion of the 1r switch actuating slide bar shown in Fig. 11.

Fig. 14 is an electrical wiring diagram for the various switches and controlling solenoids.

Brielly described, the pesent machine comprises a main frame structure into which stacks of boxes are int termittently advanced by a conveyor mechanism, and each stack, as received, caused to be tilted against and held for vertical travel in a slightly forwardly inclined guideway, beneath which guideway conveyor belts operate for the advancement of the boxes from the machine and to another location as they are successivelyv released from the lower end ofthe stack. Associated with the main frame structure, at opposite sides of the stack supporting giudeway, are vertically reciprocal cross-heads mounting dogs adapted to be actuated in accordance with the nal upward travel of the cross-heads to engage with the end walls of the box which is next to the lowest in the stack, thereby to lift the stack with the exception of the lowermost box, permitting that box to be advanced. Then, ,with the downward travel of the cross-heads, the dog supported portion of the stack is lowered, and the logs caused to be released therefrom. Then in proper timing with their upward travel, they again engage with that box of the stack next above the lowermost box, and the stack slightly elevated for the release and advancement of the lowermost box; this operation being repeated with the reciprocal actions of the cross-heads until all boxes of the stack have been advanced, whereupon devices are set in motion to bring another stack of boxes into the machine for a like de-stacking operation.

Referring more 4in detail to the drawings- The machine, in its present preferred form of construction, comprises a main frame structure erected upon and secured to two parallel, horizontal, base beams 10-10 of angle iron. The main frame is made up of op osite side sections, each section comprising two paralle, upright, but somewhat forwardly inclined beams 11 and l2, and a relatively short, vertical post or leg 13 spaced therefrom; these parts at the same side of the machine beingV level of the upper eiid of leg 13 and by two vertically spaced, horizontal bars 15 and 16 across the upper end portions of the beams 11 and 12. It is to be observed, by reference to Figs. 3 and 4,. that the beams 12 are of angle iron form and disposed at the inside of the horizontal beams 16-16 with their base ilanges 'directed toward each other so that together they provide a supporting guide within and against which a stack of boxes may be supported for up and down movement, as presently explained.

The upper end portions of the opposite beams 12 are connected by a cross beam 18. Likewise, the rear ends of beams 14-14 are joined by a cross beam 20. An electric motor 21, for driving the various conveyors and operation parts, is mounted on horizontal supports 22 that are xed to the cross bar 20 and to a horizontal bar 23 extended between the beams 12-12 at' about the level of beams 14, as shown in Fig. 3.

Stacks of boxes, for example, like that shown at S in Fig. 1, are brought up to the machine for de-stacking upon paired, oorlevel conveyor chain belts 2525, shown best in Figs. l and 4. These belts operate about sprocket wheels 26-26 on a cross shaft 27 that is rotatably supported at its ends in bearings 28--28. Th'ese belts terminate adjacent the entrance to the machine as observed in Figs. l and l0. Forwardly of and near the discharge ends of the belts, a roller 29 is mounted to receive the stack thereon from the belts 25 for its iinal advancement into the machine. The roller 29 is supported for rotation on a cross shaft 30. The shaft, in turn, is revolubly mounted-at its ends in bearings 31--31 fixed to the beams 10-10 and is driven by a chain belt 32, seen best at the left-hand side of Fig. 4. The belt 32 operates about sprocket wheels 34 and 35 that are keyed on the shafts 27 and 30 respectively. A one-way driving con nection between the shaft 30 and roller 29 is effected by an over-running clutch 36, as shown in Fig. 12; the drive of the roller being in the direction indicated in Fig. l2 in order that the stack of boxes as resting thereon, will be forwarded into the machine. Extending forwardly from the roller 29, are three conveyorchain belts 37, shown in Figs. l, 4 and, 10; these being at a level that is slightly below the level of the belts 25. When a stack of boxes is advanced by belts 25 onto the roller 29', it is carried'by the latter to a position at which the stack will tilt forwardly and engage at its lower forward corner with the belts 37, as has been shown in dotted lines in Figs. 1 and and carried by the latter belts up against the inclined base anges-of the upright beams 12-12, at which the Y advance movement of the stack is checked. It is to be observed by reference to Fig. 3 that the lower ends of the beams 12-12 terminate just above the level of the lower box in the stack. Therefore, in the subsequent lifting of the upper portion of the stack from the lowermost box, the latter will be immediately conveyed forwardly and from the machine on the belts 37, as has been indicated in Fig. l wherein the advancing box is designated at b.

The clutch 36 permits a free rotation of the roller 29 for advancement of the stack thereover by the conveyor 37 when shaft 30 is not being driven.

The electric motor 21, through suitable reduction gearing designated at 21x, drives a shaft 40 which has sprocket wheels 41 and 42 fixed thereon, as shown best in Figs. l and 4. Mounted transversely of the frame, below the level of the frame beams 14-14, is a cross shaft 43 that is revolubly mounted in supporting bearings 44-44 that are fixed to the back sides of theupright beams 12-12. Revolubly mounted on shaft 43 is a sprocket wheel 45, continuously driven by a chain belt 46 that operates thereover and over the sprocket wheel 42 on the motor shaft 40.

A friction clutch, comprising a drum 48, which mounts the sprocket wheel 45 thereon, and a clutch cone 49 that is slidably keyed to the shaft 43, provides a releasable driving connection between the motor and the shaft 43. The cone is adapted to be disengaged, by automatic means, as presently explained, to discontinue the drive of the cross shaft 43.

Cross shaft 27, which operates the conveyor chain belts 25-425 on which stacks of boxes are intermittently advanced to the machine, is driven by a chain belt connection with cross shaft 43. The connection, shown best in Figs. 1 and 2, comprises the belt 50 that operates over a sprocket wheel 51 fixed on shaft 43, thence downwardly about the under sides of idler sprockets 52 and 53 revolubly mounted in the frame structure, and thence about a sprocket wheel 54 on the cross shaft 27. Thus, the con veyor belts 25 and roller 29 are driven whenever the gear 51 is driven. The disengagement of the clutch cone 49 from drum 48 will stop the advancement of stacks of boxes by the belts 25.

Mounted in each of the opposite side sections of the` main frame, are paired guide rods 56-56 on which a cross-head frame 58 is reciprocally movable parallel with the inclination of the upright beams 12. These frames are `reciprocally actuated in unison by means of pitman rods 59 pivotally connected therewith and with crank arms 60 mounted to rotate about stub shafts 61 fixed in bearings 62 applied t9 the cross bars 16 of the main frame structure. Relatively large sprocket wheels 63-63 are revoluble on the shafts 61-61 and mount the arms 60 thereon as seen in Fig. 1. The two sprocket wheels and crank arms are driven in unison by means of chain belts 64-64 extended ythereabout and about relatively small sprocket wheels 65--65 fixed on a cross shaft 66; rthis latter shaft being mounted across the back side of the upper portion of the stack guide frame formed by the upright beams 12-12 and revoluble in bearings 67-67, as noted in Figs. 1 and 4.

The cross shaft 66 is driven from the motor 21 by means of a chain belt 70 that operates about the sprocket wheel 41 on the motor driven shaft 40 and a sprocket wheel 71 on a clutch sleeve 72 that is revoluble on shaft 66 and equipped with a clutch drum 73 adapted to be engaged by a sliding clutch cone 74 that is keyed on the shaft and is shiftable into and out of driving contact with the'drum by means presently described.

, With the understanding that when the shaft 66 is being revolubly driven, the wheels 63--63 will be driven in unison and will revolve the crank arms 60-60 therewith to eect the up and down reciprocal movements of the crosshead frames 58-58 to effect the lifting and then the lowering actions of the stacked boxes, as will now be described.

'Mounted on each of the cross head frames 58 is a pair of box lifting dogs; each dog, designated generally by numeral 85, being like that shown in Fig. 7. The dogs at opposite sides of the machine are adapted, as the cross heads 58 are being moved upwardly, to be engaged with the opposite end walls of the next to the lowest box in the stack of boxes as moved into position between them against the inclined beams 12-12, for the purpose of slightly lifting that portion of the stack which is above the lowermost box, whereupon the lowermost box will be elsed for advancement from the machine on the belts 37. Then, with the subsequent downward travel of the cross heads, the dog supported part of the stack will be lowered and rested upon'the roller 29 for support andthe dogs released therefrom.

Each dog comprises a lever arm a which is formed at its swinging end with an inturned portion 8S on which a block 86 is fixed. Mounted in each block are inwardly and upwardly directed teeth 87 to be-holdingly engaged with the box end walls.

The lever arms 85a, of the pairv of dogs at each side of the machine, are fixed on opposite ends of a horizontal shaft 88 that is rotatably supported in bearing members 89-89 secured to the cross heads. Each shaft 88 has a short actuating arm 90 xed thereto, and the lower end portion of a push rod 91 pivotally attached thereto, as at 92 in Fig. 7, with the upper end portion of the push rod extended slidably through a hole in the upper member of the cross head, as observed in Fig. 5. Fixed on the upper end of the rod is a nut 95, and held under compression between the nut and cross head member, is a coiled spring 96 that operates through rthe connections described, to urge the dogs toward disengaged position, as seen in Figs. 6 and 7.

When the cross heads 58--58 are in their lowered positions, all dogs 85 will be disengaged and held outwardly from the box ends as shown in Figs. 3 and 6. When the cross heads. are moved upwardly, the paired dogs, in this position, move therewith. But as the cross heads reach positions about two inches from their upper limits of travel, the upper ends of the rods 91 mounted therein are brought directly into end to end contact with trip rods 98 that are located at opposite sides Yof the main frame, and slidably mounted in the corresponding cross members 14 and 15 as seen in Figs. l and 5. Each rod 98 has a collar 99 fixed about its lower end portion adapted to engage the cross meniber 14 to limit the downward movement of the rod. Coiled springs 100 are disposed about the rods 98 between the nuts and the cross members 15 to resist upward movement of the rods. The springs 100 are stronger than the springs 96, thus when the upper ends of rods 91 engage the lower ends of rods 98 with the upward travel of the cross-head frames, the rods 91 are temporarily stopped against farther upward travel while the cross heads to continue to move up, and the shafts 85 are rotated in a manner to cause the paired dogs thereon to be swung inwardly into contact willi the opposite end walls of the adjacent box, as has been shown in dotted lines, at 85x in Fig. 6. ln this ar rangement, the box engaged is the one next above the lowest box in the stack. Then, with the continued and nal upward travel of the cross head 58--58, the teeth 87 of the dogs bite into the wooden end walls of the box and cause the slight lifting of the engaged box and that part of the stack supported thereon. The lower box is thereby left free for advancement from the machine by the conveyor belts 37 on which it rests and which are continuously driven.

It will further be explained that after the dogs 85 have engaged with the box end walls, the farther upward travel of the cross heads causes the trip rods 98 to be lifted against the pressure of the springs 100.

When the lowermost box is freed by the lifting of the upper portion of the stack therefrom, it is immediately advanced from the machine. Then, with the lowering of the cross heads 58, the supported portion of the stack is lowered onto the cross roller 29. However.

` connected to a toggle linkage 120 lever 121 to engage and disengage momias h cross-shafts 88 are rotatably actuated through the mediacy of the rods 91 and lever arms 91),l thus to` swing the dogs outwardly and clear of the boxends. Thus, with each upward movement of the cross heads, the dogs are caused to engage and lift a partl o f the stack, to free the lowerinost box -which is immediately) advanced 'from the machine. With their downward movements, the supported part of the stack is lowered onto roller 29, and the dogs disengaged. Thus, the stack will finally bedepleted, and the machine is ready to receive another stack. Stacks may be made locatedron the feed belts at regular or irregular inter- `vals of spacing, but should be properlyvpositioned for entry into the machine. Stack alining guides may be fixed in the frame for this purpose.

The means for periodically advancing the feed belts -25 for the bringing of c to the machine for de-stac g will new be described:

The automatic, control of the machine for the advanceinent of the stacks of boxes and for the de-stacking operations is effected through'the use of two s9- lenoids and 112 which are xedly mounted .in the machine, as seen in Figs. l and 3, with their core bars operatively connected with the shifting mechanisms of the clutch cones 49 and 74 `as associated with shafts 43 and 66. It is shown in Fig. 3 that solenoid 110 has 'I its core bar pivotally connected by a link 113 with a thatat one end is pivoted, as at 115, and at its other end is pivoted, as at 117 to a lever arm 118. Lever 118 is pivoted at its upper end to the cross bar 23, and at its lower end has a pin and slot connection 119 with the shifting collar 49' of solenoid 110, its core toggle linkage 114 to a fixed member 116,

bar straightens the toggle linkvage and thus swings the lever118 laterally and engages the clutch to drive shaft -43. When the solenoid is de-energized, the clutch is caused to be disengaged.

Likewise, the solenoid 112 has it core bar pivotally which actuates a with the clutch vdrum 73 to drive the shaft 66.

Operating in shifts the clutch cone 74 into and from driving contact with drum 73, is a brake mechanism which is shown in Figs. 3 and 4 to comprise a fixed plate 122 and a disk 123 xed on a sleeve 123' that is slidably keyed on shaft 66. A cross bar 124'pivotally connects the lower end of shift lever 121 with the sleeve 123 (see Fig. 3) in such manner that with the shifting of the clutch cone 74 into and from driving engagement with the drum 73, the brake will be disengaged and engaged, thus to prevent any coasting of the machine after the clutch is disengaged. It is shown also in Fig. 3 that a shift lever 125 is pivoted at 125 in the frame with its lower end pivotally connected, as at 126, to the brake sleeve 1.23'. A spring 127 is attached to the upper end of the lever 125 and to the frame to immediately throw the brake to its braking position upon deenergization of the solenoid 112.

The wiring for the electric circuits of the two solenoids is shown in Fig. 14. A source of electrical energy is indicated by wires x and y to be connected through switch C with circuit wires 128 and 129. Associated with the control circuits are six switches, designated by reference numerals 131, 132, 133, 134,

and 136. For a proper understanding ofthe operation, 136 are normally closed. Switch 133 is normally open. Switch 134 is a double switch having one outlet 134a normally open and its other outlet 134b normally closed. All switches have push button actuators. A circuit the prepared stacks of boxes the clutch cone 49. Upon energizing the` the clutch cone 74 respectively.

The switch 131 is located in the upper part of the ready and`l to the switch 134 and wires 151 anl152 connect the opposite sides of switch 132 with the wires 142 and 150,

frame structure at the left-hand side in Fig. 3, for actuation by a lever supported by a vertical pivot pin 161, as shown in Figs. 8 and 9. One end of the lever 160 has a laterally turned end portion 160i: disposed to engage the push button of the switch. The other end `of the lever is disposed. in. position to be engaged bya stud on the adjacent sprocket wheel 63 as the wheel rotates to a-position at which the crank arm 60 is brought to the upperlimit of its rotation.

. The switches 132 andv 131, as seen in Fig. 8, and are adapted to vbe simultaneously actuated by a lever 166 that is directly below lever 160 and pivoted onv pin 161 with one end disposed to engage the switch buttons simultaneously, and with its other end portion extended to a position to be actuated by a stud 167 when the lever arm 6G is downwardly directed, as seen in Fig. 8.

Springs 168 and 169 bear against the levers 160-7166 l to yieldingly urge them to positions at which they disengage the switchesl controlled thereby.

Pivoted on the bracket is a lever 172 that depends to a g position at which its free end will be engaged by the stack of boxes as disposed in the inclined frame and thereby actuated to a position at which it will depress the conjunction with the lever 121 which it is to be known that switches 131, 132, 135 and v connection 140 leads from wire 128 to one side of solenoid 112, and a wire 141 leads from the other side of this solenoid to one side of switch 131. Wires 142 and 143 lead from the other side of switch 131, re* spectively, to the outlet 134a of switch 134 and to one side of switch 135. The other side of switch 135 is connected by wire 144 with wire 141.

push button of switch 134. A spring 176 actsvagainst Ithe lever to push it away. from the switch when disengaged by the stack.

'Ihe switches 135 and 136 are located in the base of the frame structure, as noted in Fig. ll, and mounted on a ixed member 180 attached to beam 10. Extended transversely of the frame, as shown in Figs. 10 and 11, is

a cross shaft 182. A lever arm 183 is xed to this shaft and extends into the path of travel of boxes rested on the conveyors 37, as will be understood by reference to Fig. l0. Thus, when a stack of boxes is moved into position and leaned against the inclined support formed by beams 1212, the lever 183 effects a rotative movement of the shaft 182. Fixed to the shaft, as noted in Fig. l1, is an upwardly directed lever arm which pivotally vconnects, as at 191, with one end of a slide bar 192, ex-

tended along the adjacent bar 10 and formed with a hook portion 1.95 that engages over the top edges of the bar as a sliding support therefor. This end of the .bar has an inturned flange 196, see Fig. 13, which is adapted to press against the push buttons of the switches 135 and 136 whenever a box is in position at which it depresses the lever 183.

When no box is in position to engage and depress the lever 1.83, the switch control slide is disengaged from the switches by pull of a coiled spring 199 which is attached to the base beam 10 and the lever arm 190, as shown in Fig. ll.

The manner in which the solenoids 110 and 112 are electrically connected with the power lines x and y through the control switch` C and the various auxiliary switches, places the solenoid 110 under control of switches 133, 134b and 136, and places solenoid 112 The motor 21 is energized and switch C is closed.

Shaft 43 is thereby caused to be driven through the belt connection 46 and clutch parts 48-49, and the conveyor belts 25-25 and roller 29 to be driven through the belt connection 50 with cross shaft 27, thus to advance a stack of boxes on the belts 25 from the full line to the dotted line vposition of Fig. l. As the stack passes onto and over the roller 29, it is permitted, by reason of the disposition of the conveyor belts 37 at a lower level than the roller, to lean forwardly at the top until the lower forward corner of the stack comes into supporting con- 133 are directly below switch y any further advance of the box at the lower end of the stack. n

It is also to be understood, as seen in Fig. 10, that when the stack of boxes is moved to this forwardly inv clined position of support by beams `12, the lowermost box of the stack rides over the switch control lever arm 183, actuating it ownwardly. Also, the forward wall of the box which is next to the lowest in the stack comes into contact with the`switch actuating lever arm 172 to depress it to actuate switch v134. The downward actuation of lever arm 183 rotatably actuates shaft 182 to swing arm 190 to shift the slide bar 192 in a manner whereby to cause its end flange 196 to contact the switches 135 and 136, which are normally closed, to open them. Ihe depressing of the actuating'lever arm 172 of switch 134, closes the circuit through its connection 134a and opens the circuit through its connection 134b.

At the start of the de-stacking operation, the circuit through solenoid 110 was closed-by reason of the setting of various switches. Now, the actuation of lever 172 and opening of the circuit through 134b, de-energizes the solenoid 110, whereupon the clutch cone 49 is disengaged to discontinue driving of shaft 43 and conveyor belts 25-25 and roller 29. The closing of the circuit through switch outlet 13441 coincident with opening contact 134b, energizes the solenoid 112 and sets the clutch cone 74 in drum 73 to drive the cross shaft 66 from which the sprocket wheels 63-63 and the attached crank arms 60-60 are driven in unison through the chain belts 64 operating about the sprocket wheels 63. With the setting of this clutch, the switch control wheel 63, shown in Fig. 8, is rotated. This causes switch arm 166 to be disengaged by its actuating stud 167 and then open switch 132r to be closed and the then closed switch to be opened; that is, these switches then assume their normal positions. .'I'hen, when the wheel 63 reaches a half turn, the stud 165 moves into operating contact with switch lever 160 and actuates it to actuate the normally closed switch 131 to its open position. This rotation of the wheels 63-63 results in the lifting of the stack, as was previously explained.

The opening of switch 131 de-energizes solenoid 112, thus disengaging the clutch cone 74, causing the wheels 63-63 to stop rotation thus to hold the stack lifted, while the lowermost box of the original stack, thus freed, leaves the machine on conveyor belts 37. As soon as the released box moves beyond the switch arm 183, the arm swings upwardly, and the shaft 182 is rotated by spring 199 to shift the slide bar 192 back, thus to disengage the switches 135 and 136, which have been held open thereby, allowing both to close, whereupon the solenoid 112 is energized through switch 135 and switch contact 134a, setting the clutch cone 74 controlled thereby to drive shaft 66 and again rotate the crank arms 60 to cause the supported portion of the stack to be lowered onto roller 29 and the dogs to be disengaged from the lowermost box. As the arms 60-60 continue to rotate, the cross heads 58-58 move upwardly causing the dogs 85-85 to engage and lift the then remaining part of the stack, with the exception of the lowermost box, for the release and advancement of the said lowermost box by the conveyors 37. This lifting and lowering operation is repeated until the stack is depleted. As the last remaining box of a stack isy lowered onto the belts 37, the switch lever 172 is disengaged, allowing the switches 13411 (normally open) and 134b (normally closed) to resume their normal positions. The closing of switch contact 134b energizes solenoid 110, thus setting the clutch parts 48 and 49, to drive shaft 43 to again advance the belt conveyors 25-25 to bring another stack of boxes into de-stacking position against the inclined support 12-12, whereupon the switch control lever 172 is depressed to close switch 13441, and open switch 134b and lever 183 is depressed to open switches 135 and 136 so that another de-stacking operation is started. 2 v

Having thus described my invention, what I claim 'is new therein and desire to secure by Letters Patent is:

l. A box de-stacking machine comprising a continuously horizontally traveling conveyor, a substantially upright stack-guide frame spaced thereabove a distance slightlygreater than the height of a box, means for disposing a stack 'of"boxes on the conveyor for advancement thereon against said stack guide frame in a manner whereby the stack is restrained against advancement as a unit, a roller disposed transversely of the direction of the said traveling lconveyor and ,immediately in advance thereof and adapted to receive the stack thereon for support with the lowermost box of .the stack engaged frictionally against the' traveling conveyor for its ready advancement when freed, stack lifting dogs located at opposite sides of .said frame, means for vertically reciprocating said dogs in unison, means for causing said dogs to be simultaneously engaged with the stack, to lift the portion thereof that is above the lowermost box, thus to -free the latter for advancement by the conveyor on which it rests and to then lower the lifted portion of the stack onto the conveyor, and means for disengaging the dogs from the stack at the end of the downward travel.

2. A machine as in claim l wherein the stacking guide frame is forwardly inclined and wherein said roller is mounted at a slightly higher level than' said conveyor to receive the stack thereon for support in an unbalanced condition to `cause it to lean against the frame and the lowermost box thereof is caused to frictionally engage the conveyor for its ready advancement upon being freed.

3. A destacking machine as recited in claim ll wherein the stack guide frame is forwardly inclined for the restraining of the stack in a leaning condition as supported on said roller and wherein the means for disposing the stack of boxes in the machine comprises a delivery convveyor belt operating at a level slightly above the level of said horizontally traveling conveyor for delivery of the stack onto said roller.

4. In a box de-stacking machine, a horizontal moving conveyor, a stack-guide frame spaced thereabove, and adapted to check a stack of boxes supported thereon against advancement as a unit while supported on the said conveyor, an intermittent conveyorv for delivery of stacks of boxes onto the moving conveyor a vertically reciprocating means operable during its upward movement to lift a part of a checked stack thus to free the unlifted portion for advancement by the conveyor from the stack, and, by its downward movement to lower the lifted portion of the stack along the frame onto the moving conveyor, a continuously driven shaft, a driving shaft for the intermittent conveyor, a releasable clutch normally maintaining a driving connection between the driven shaft and the conveyor driving shaft, and means controlled by the said stack lifting means and lower box of the 'stack to cause the said clutch to be disengaged incident to the stack being lifted and while the box that is thuskfreed is moving from beneath the lifted part of the stac Y 5. A box de-stacking machine comprising a horizontal conveyor intermittently operable for the advancing of stacks of boxes thereon in succession into the machine. a transverse roller for receiving each stack thereon from the conveyor for support and de-stacking, a continuously traveling conveyor continuing from the roller, at a slightly lower level, a stack-guide frame disposed above the said traveling conveyor a distance that is slightly more than the height of one box and adapted to sustain the stacked boxes thereagainst while supported by said roller, and said stack-guide frame being forwardly inclined in a manner to cause the stack to rest therein and the lowermost box to frictionally engage with the traveling conveyor, guide rods at opposite sides of and parallel with the guide frame, cross-heads reciprocally mounted on said rods, stack lifting dogs on said cross-heads, means for reciprocating the cross-heads in unison, means for causing said dogs thereof to be engaged with the stack adjacent thelowermost box as the cross-heads move upwardly, for lifting the stack to free the said lowermost box for its forward conveyance by the traveling conveyor, and then to lower the lifted portion of the stack onto the roller and conveyor and means for disengaging the dogs from the lowered stack preparatory to a repetition of the stack lifting operation.

6. A machine as recited in claim 5 wherein the said roller is driven in unison with the intermittent conveyor through an over-running clutch connection and is permitted to turn freely for the removal of a freed box by the traveling conveyor.

7. A box de-stacking machine comprising a trst conarcanes 10 veyor operable intermittently for the advancement theiebe advanced into the machine, a traveling conveyor on on of stacks of boxes in succession into the machine, a which destacked boxes are adapted to be conveyed from continuously'traveling conveyor disposed to receive the the machine, a stack-guide frame disposed above the stacks of boxes from the said first conveyor and operable second conveyor to receive a stack of boxes thereagainst for conveyance of de-stacked boxes from the machine, a .from the said horizontal conveyor to restrain the stack stack-guide frame disposed above the traveling conveyor against advancement as a unit by the said traveling cona distance slightly more than the height of one box and veyor, means for intermittently lifting a part of the rein position to be engaged by a stack as delivered to the strained stack in the frame to free the unlifted portion traveling conveyor to restrain the stack against advancefor its advancement by the said traveling conveyor, an ment as a unit, vertically reciprocating 'ting means op- 10 an lelectrically operable means for energizing the first erable, with each upward movement, to pick up that conveyor, an electric circuit for said means, and a switch part of thestack above the lowermost box for the release normally held open by the stack as disposed on the maof said lowermost box for its removal from the stack by chine, operable incident to the reducing of the height of the traveling conveyor, and then to lower the lifted part the stack to less than the spacing of the said guide frame of the stack onto the said conveyor, and devices controlled above the second conveyor, to close said circuit and by the stack lifting means and lowermost box of the cause the horizontal conveyor to be advanced to deliver stack to effect a momentary stopping of the lifting means a stack of boxes into the machine. t when the. stack is in lifted position and while the freed 10. A box destacking machine comprising a normally box is being cleared from the stack. inactive horizontal conveyor upon which stacks of boxes 8. In a box stacking machine, in combination, a horimay be advanced into the machine, a traveling conveyor `zontal, continuously traveling conveyor, a box guide on which destackcd boxes are adapted to be conveyed frame disposed thereabove for receiving a stack of boxes from the machine, a stack guide frame disposed above thereagainst as carried on said conveyor, to restrain the the second conveyor to receive a stack of boxes therestack against advancement as a unit, a pair of crossagainst from the said horizontal conveyor to restrain the heads mounted at opposite sides of the frame for reciprostack against advancement as a unit by the said traveling cation parallel with the stack, means for reciprocating conveyor, means for intermittently lifting a part o the the cross-heads, a horizontal shaft rotatably mounted restrained stack in the frame to free the unlifted'portion in each cross-head, lever arms xed to said shafts, dogs for its advancement by said traveling conveyor, means mounted by said lever arms to swing therewith into and for energizing the first conveyor incident to the reducing from lifting contact with a box in the stack, means yield- 3Q of the height of the restrained stach to less than the ingly urging the dogs away from the stack, an actuating spacing of the guide frame above the second conveyor, lever for each shaft, a push rod movable with each crossthe last means including first control mechanism mounted head and operatively attached to the corresponding actuon the guide frame to be engaged by the restrained stack, ating lever arm, and stop members in the frame against and second control mechanism mounted below the guide which said push rods are caused to engage as the crossframe to be engaged by the restrained stack. heads move to their upper and lower limits of travel, to actultef: thhshilffts to eigage the dogsvllith alliiox tltllie i References Cited in the file of this patent stac or e ting o a portion. of e stac an us free the unlifted portion for clearance from the machine UNITED STATES PATENTS by the traveling conveyor and to then lower the lifted 40 1,782,955 Biggert Nov. 25. 1930 portion of the stack onto the conveyor, and to disengage 2,028,410 `Rapisarda a the dogs from the lowered stack. 2,089,385 Llewellyn 9. A box de-stacking machine comprising a normally 2,200,708 Towne et aL v inactive horizontal conveyor on which stacks of boxes may 2,258,461 Marsden Oct. 7 194 

